Studies on schistosomiasis. 10. Development of Schistosoma mattheei in sheep infested with equal numbers of male and female cercariae.

VAN RENSBURG, L. J. & VANWYK, J. A., 1981. Studies on schistosomiasis. 10. Development of Schistosoma mattheei in sheep infested with equal numbers of male and female cercariae. Onderstepoort Journal of Veterinary Research, 48, 7786 (1981). The development of the female Schistosoma mattheei was significantly higher than that of the male (PP<0,1). A total of 609 male and 800 female worms was recovered from the 1 200 cercariae of each sex used for TABLE 1 Development of cercariae and worm distribution Worm distribution infestation, a mean development of 58,6% (50, 8% for the male and 66 ,7% for the female cercariae, Table 1 ). The difference in development of the 2 sexes is highly significant (P<O,OOOl). The worms recovered from the mesentery comprised 93, 5% of the total (99, 3% of the males and 89 , 1 % of the females), while 5 , 2% (0 , 3% of the males and 8, 9% of the females) were recovered from the liver and I , 3% from the lungs (0, 3 % of the males and 2,0% of the females) . One hundred and eleven of the 713 female worms recovered from the mesentery were small and resembled immature females in unisexual infestations. The remainder of the females and all the males were fully developed adults . The large female worms (602) were very similar in number to the males (605) from this site. Worm distributions according to size and intrauterine egg count distributions are given in Fig. 1-9. The lengths of female worms from the mesentery fell into one of the 2 distinct groups and are designated for convenience as either "large" or "small" females. The length of only one worm was intermediate between the 2 groups; this worm was empirically grouped with the large females. The worm measurements and intra-uterine egg counts are summarized in Table 2, and the numbers of worms measured in Table 3. Worm lengths The mean lengths of the "large" and "small" female worms from the mesentery of Sheep 1-12 (killed 74-76 days after infestation) were 21 , 8 mm (range 15-27) and 9, 7 mm (range 4-13) respectively (Table 2, Fig. 1-3). Only small females were recovered from the mesentery of the remaining 3 sheep; those from Sheep 13 (killed 71 days after infestation) had a mean length of 7,5 mm (range 6-9 mm) and those from Sheep 14 and 15 (killed 134-137 days after infestation) had a mean length of 11,5 mm (range 4-15 mm). Total worms Mesentery Liver Lungs CercaDurariae Sheep tion failed to (days)* <i' % penetrate (%) 3 3 <i' 3 <i' 3 <i' deveI I lopLarge Small Total ment 1. .. . .. . 74 42 41 5 46 0 6 0 0 42 52 46,0 1,5 2 . . ... . . 74 40 40 22 62 0 1 1 6 41 69 55,0 0,5 3 .... .. . 74 52 52 2 54 0 8 0 0 52 62 57,0 4,5 4 . .. . ... 74 50 50 5 55 0 10 0 0 50 65 57,5 1,0 5 .... .. . 75 39 38 5 43 0 2 0 0 39 45 42,0 8,0 6 .... .. . 75 61 61 18 79 0 1 0 0 61 80 70,5 2,5 7 .... ... 75 66 66 3 69 0 8 0 1 66 78 72,0 1,5 8 .. .. .. . 75 62 62 4 66 2 11 0 0 64 77 70,5 1,0 9 ....... 76 39 39 13 52 0 4 1 4 40 60 50,0 7,0 10 .. . . . .. 76 67 66 3 69 0 1 0 5 67 75 71,0 4,5 11 .. .. ... 76 34 34 20 54 0 7 0 0 34 61 47,5 7,5 12 ..... .. 76 53 53 11 64 0 12 0 0 53 76 64,5 1,0 Mean . ... 75 50,4 50,2 9,3 59,4 0,2 5,9 0,2 1, 3 50,8 66,7 58,6 3,4 S.D.*** .. . 11,6 11,7 7,3 10,5 0,6 4,1 0,4 2,3 11,6 11 '1 10,9 2,8 c.v. (%)** 23,0 23,3 78,5 17,6 300,0 69,5 200,0 176,9 22,8 16,6 18,6 82,4 Total. .. 605 602 111 713 2 71 2 16 609 800 ,-1 * Days between infestation and death **Coefficient of variation ***Standard deviation 78 L. J. VAN RENSBURG & J. A. VAN WYK TABLE 2 Comparative worm sizes and numbers of intra-uterine ova Worm measurements and numbers of ova Dimension and site Sheep 1-12 (infested Sheep 13 (infested Sheep 14 + 15 (infested of worms with o + '( worms with '( worms only with '( worms only for 74-76 days) for 71 days) for 134 days) Mean I S.D.t Mean I S.D.t Mean I S.D.t Lengths (mm) Mesentery (large '() .............. . .... .. 21 ,8 2,0 Mesentery (small '() ................. . ... 9,7 1,8 7 , 5 0,8 11 '5 1 '7 Liver . ...... .......... ...... .... .. ..... 9,9* 1,9 6,1 0,7 9,4 2,3 Lungs . .... .... . ................... . ... 7 , I 2,4 5,8 I ,0 8,5 2,8 Breadths (J.<m) Mesentery (large '() . .... ... ........... .. 250 29 Mesentery (small '() ........ .. .. .. .. . .. . . 171 40 158 20 231 41 Liver .. . ... .. . ..... ..... . ...... . ....... 164* 23 174 19 227 54 Lungs ... .. .. ... . . . .. .. . .. ..... .. .. ... . 136 26 152 7 Ova in uterus (number) Mesentery (large '() ......... . . ... ...... . . 23,0 15,0 Mesentery (small '() .... . ... . ...... . ..... 5,8 10,6 0 0 2,0 3,0 Liver .. ..... .. . .. ..... . ... . ...... . ..... 3,4* 6,1 0 0 0,7 1,4 Lungs .... . . . .. ..... . .... . ..... .. . ..... 0,8 3,0 0 0 t Standard deviation *Two large '( worms (one broken and the other 18 mm in length, 220 J.'m in breadth and containing 6 ova in the uterus) recovered from the liver of Sheep 8, were disregarded for calculation of these mean values TABLE 3 The number of worms measured or examined for ova for the data summarized in Table 2 Sheep Locality I I 1-12 13 14-15 Mesentery (large '() ..... . 369 Mesentery (small '() ... .. . 99 53 94 Liver ........... .. ...... 50 46 92 Lungs .. .. ............. .. 16 8 36 With one exception (Sheep 8), all females from the livers were small, having a mean length of 9, 9 mm (range 6-13), 6, 1 mm (range 4-8) and 9, 4 mm (range 3-13) in Sheep 1-12, 13 and 14 & 15 respectively. One of the large females from the liver of Sheep 8 was 18 mm in length; the other was broken and could not be measured. The mean length of worms from the lungs was 7, 1 mm (range 4-12) in Sheep 1-12; 5,8 mm (range 4-7) in Sheep 13 and 8 , 5 mm (range 4-13) in Sheep 14 and 15. Worm breadth The mean breadth of the large female worms recovered from the mesentery of Sheep 1-12 was 250 J.Lm (range 146-323, see Table 2 and Fig. 4-6), whereas that of the corresponding small females was 171 J.Lffi (range 73-322). The mean breadth of the females from Sheep 13 was 158 J.Lm (range 117-205) and from Sheep 14 and 15 was 231 J.Lm (range 117307). The mean breadth of female worms from the livers of Sheep 1-12, Sheep 13 and Sheep 14 and 15 was 164 J.Lm (range 117-220), 174 J.Lm (range 132-220) and 227 J.Lm (range 88337) respectively, while that of worms from the lungs was 136 J.Lm (range 88-190) and 152 J.Lm (range 146-151) for Sheep 112 and Sheep 13 respectively. The breadth of worms from the lungs of Sheep 14 and 15 could not be measured because the worms were damaged after the lengths had been determined. The breadth of one of the 2 large female worms from the liver of Sheep 8 was 220 J.Lm. TABLE 4 Infestation and worm recovery data of sheep 13-15 infested with '( worms only Interval Worm development Worm distribution(%) between Cercariae* Sheep No. infestation I and autopsy (No.) Number of %* Mesentery Liver Lungs (days) worms development 13 . ....... ........ ... ... . . .. 72 1 500 742 50 10,7 88,1 1,2 14 .. ......... ..... ... . . ..... 137 960 732 76 61,4 36 , 1 2,5 15 .......... . ........ .. ..... 134 1 040 930 89 19,0 75,4 5,6 " Because small numbers of cercariae were available, the infective doses could not accurately be determined (Van Wyk & Groeneveld, 1973) 79 STUDIES ON SCHISTOSOMIASIS. 10